Calibration of laboratory derived indices for non-target arthropod risk assessment with field data for plant protection products.

The Hazard Quotient (HQ) compares field application rate to intrinsic toxicity assessed with sensitive indicator species. As a hazard indicator for risk assessment, the HQ must be calibrated against measured effects under field conditions. Because protection goals may be context specific, we analyse how choice of acceptance criteria affects setting of the HQ and calibrate HQ for various scenarios under the strict condition that no false negative conclusions may be reached. We use Non-Target Arthropod toxicity data from laboratory studies on inert (Tier 1) and on natural substrates (Tier 2) and calibrate the HQ using application rates and arthropod abundance counts from field studies in orchards, arable fields, and hay meadows in 34 locations in Western Europe. With 21 formulations (17 active substances) tested in mostly multi-rate field studies, our reference data base has 120/121 values at Tier 1/Tier 2, respectively. We use the Proportion of Affected Taxa and Duration of Effect to jointly define acceptance criteria, starting with No Observed Effects. Absence of field effects is correctly predicted with HQ < 1.3 at Tier 1 and HQ < 0.48 at Tier 2, but these settings result in a high proportion of false positive outcomes. Increasing accepted duration of effect from 0 to 4 to 8 weeks results in HQ-threshold changes from 1.3 to 6.4 to 250 for Tier 1 studies and from 0.48 to 1.1 to 5.7 for Tier 2 studies. This coincides with a clear decrease in false positive outcomes. Recovery within a year is correctly concluded for 73% of the products passing the corresponding Tier 1 HQ < 2600 and for 92% of products at Tier 2 (HQ <230). Our analysis shows that the calibration is appropriate for a broad geographical range, for in-field and off-field situations and for phytophagous and non-phytophagous species alike.

The Role of Source-Sink Dynamics in the Assessment of Risk to Nontarget Arthropods from the Use of Plant Protection Products.

The concept of source-sink dynamics as a potentially important component of metapopulation dynamics was introduced in the 1980s. The objective of the present review was to review the considerable body of work that has been developed, to consider its theoretical implications as well as to understand how source-sink dynamics may manifest under field conditions in the specific case of nontarget arthropods in the agricultural environment. Our review concludes that metapopulation dynamics based on field observations are often far more complex than existing theoretical source-sink models would indicate, because they are dependent on numerous population processes and influencing factors. The difficulty in identifying and measuring these factors likely explains why empirical studies assessing source-sink dynamics are scarce. Furthermore, we highlight the importance of considering the spatial and temporal heterogeneity of agricultural landscapes when assessing the population dynamics of nontarget arthropods in the context of the risk from the use of plant protection products. A need is identified to further develop and thoroughly validate predictive population models, which can incorporate all factors relevant to a specific system. Once reliable predictive models for a number of representative nontarget arthropod species are available, they could provide a meaningful tool for refined risk evaluations (higher tier level risk assessment), addressing specific concerns identified at the initial evaluation stages (lower tier level risk assessment). Environ Toxicol Chem 2021;40:2667-2679. © 2021 ERM, FMC, Syngenta, Bayer AG, BASF SE, Corteva agriscience. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Authors' response on Hoppe et al. (2015) "Effects of a neonicotinoid pesticide on honey bee colonies: a response to the field study by Pilling et al. (2013)". Environ Sci Eur (2015) 27-28.

The published Commentary by Hoppe et al. (Environ Sci Eur 27-28, 2015) makes a number of strong criticisms of Pilling et al. (PLoS One 8:e77193, 2013), which this authors' response will show are either wrong, inaccurate or misleading. A selection of these misrepresentations include a claim that technical thiamethoxam was used rather than the commercial product. This is not true. Pilling et al. (PLoS One 8:e77193, 2013) clearly state that formulated commercial products were used which also included fungicides. It is claimed that there was a failure to quantify colony losses in winter. Again this is not true. These data were readily extractable from the original paper. It is claimed that 70 % of the colonies did not survive. For a multiple year study this is very misleading. The annual colony loss rate was 14.8 % for treated colonies and 16 % for control colonies, well within background colony loss rates reported by the EC Epilobee EU monitoring programme. Concerns are also raised regarding the PLOS One reviewing process. The reality is that Pilling et al. (PLoS One 8:e77193, 2013) was extensively reviewed by five referees during the original review process, followed by a second post-publication editorial review. These inaccurate and misleading statements are then used to infer that the data, methodology and conclusions of low risk to honeybees from Pilling et al. (PLoS One 8:e77193, 2013) are untruthful and misleading. This inference is both absolutely untrue and inappropriate. Pilling et al.'s (PLoS One 8:e77193, 2013) paper is a summary of one the most comprehensive set of field studies ever conducted on honeybees, a fact recognised within both the second review by PLOS One and within the published EFSA Evaluation of Thiamethoxam.